Despite the great experimental effort carried out over the past years by means of different techniques, the segmental dynamics in the model blend system poly(vinylethylene)/polyisoprene (PVE/ PI) is still a topic of strong debate. One of the most controversial questions is the possibility of a bimodal distribution of segmental relaxation times for polyisoprene in the blend. In this work, we have combined a microscopic technique, quasielastic neutron scattering (QENS), with molecular isotopic labeling and broad-band dielectric spectroscopy. The measurements have been carried out on the same samples and at the same temperature (270 K). By means of this combination, we have shown that all the PI in the miscible blend sample PVE/PI (50 wt % PVE-50 wt % PI) dynamically behaves very close to pure PI. In contrast, the R-relaxation of PVE component in the blend is drastically "plasticized". In addition, it has been shown for the first time by QENS that the secondary -like processes seem not to be modified by blending, at least for the blend component displaying the higher T g. These experimental facts contradict many of the results previously published about the dynamics of the PI/PVE system, and as far as our knowledge, they cannot be explained in the frame of the models presently available for polymer blends dynamics.

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A thermodynamic theory is used to calculate the dielectric properties of epitaxial thin films grown on cubic substrates imposing biaxial tension on the film prototypic cubic state. For such “tensile” substrates, the theory shows that, in a conventional plate–capacitor setup, the films should display only a monotonic variation or a broad maximum in the temperature dependence of the permittivity and an apparent absence of the hysteretic polarization behavior. Changes of the Curie–Weiss temperature and constant caused by the mechanical film/substrate interaction are also predicted. Theoretical results agree with the observed properties of columnar-structured BaTiO3 and SrTiO3 thin films grown on Si.

In order to investigate the origin of the often invoked nanoheterogeneities in miscible polymer blends, we have performed quasielastic neutron scattering experiments on the component dynamics within the miscible polymer blend polyisoprene/polyvinyl ether including the pure components as a reference. We find that the apparent local heterogeneities observed by spectroscopic techniques originate from the chain specific crossover properties between entropy driven and local chain dynamics and are, thus, a purely dynamical phenomenon.